In the field of wireless communication, broadband wireless access technologies are becoming more and more important to meet the demand for high-speed, high-volume data communications. In the current third-generation wireless access system, direct-sequence code division multiple access (DS-CDMA) is employed to improve frequency efficiency and transmission efficiency by means of one-cell frequency reuse. A base station used in such a system has to communicate with mobile stations present in multiple sectors and therefore it is necessary to overcome the problem of multiple access interference (MAI). A conventional method to overcome multiple access interference in uplink communications is disclosed, for example, in non-patent document 1.
[Non-patent document 1] E. Hong, S. Hwang, K. Kim, and K. Whang, “Synchronous transmission technique for the reverse link in DS-CDMA”, IEEE Trans. on Commun., vol. 47, no. 11, pp. 1632-1635, November 1999